1. Field of the Invention
This invention relates to electronic circuits, and more particularly, to circuitry for isolating power domains from one another during power down operations.
2. Description of the Related Art
In many modern integrated circuits (ICs), the circuitry of different functional units may be implemented within different power domains. The reasons for implementing circuits in different power domains may vary. For example, some functional units may have different operating voltage requirement than others. Accordingly, circuits with different operating voltage requirements with respect to other circuits may be implemented in separate power domains.
Another reason for implementing different circuits in different power domains may be due to power saving requirements. While the circuitry of two different functional units may operate at the same supply voltage, the arrangement of an IC on which they are both implemented may require that one be capable of being powered down while the power is still applied to the other.
Although an IC may implement various functional units in different power domains, many of these functional units may be interfaced with others in other power domains. When functional units of two different power domains are both receiving power, communications between them may occur. Communications between the two functional units may be inhibited when one or both are powered down.